The keys on your laptop are the kind of item you don't pay any attention until you lose them. The "O" key came off from my Carbon X1 keyboard a few days ago. I was able to postpone the ultimate solution by a couple of days by just pushing the "O" back. But doing that five times a day got old soon. So, I took of another key - "I" - to figure out the correct alignment for the metal hooks that hold the plastic hinges in place. That was a good idea on paper except that I was able to break the hinge when installing the "I" back. After a failed attempt of gluing the hinge together with a generous amount of epoxy I gave up and decided to order replacement keys.
For this particular X1 model it was quite hard to find replacement keys, though I succeeded after going through all laptop key sellers Google and Duckduckgo could find. While waiting for two "I" and one "O" to arrive from Pennsylvania (7-21 days) I did what most people would do:
I kind of feel sorry for PrtSc key, because it has enabled me to collect an archive of accidental screenshots that I can go through in my rocking chair in my golden years to see what I did when I was still relatively young.